"I think the biggest piece of fake news in the election was that Donald Trump couldn't win," Conway told CNN's Jake Tapper during a discussion at Harvard Kennedy School's Institute of Politics, referencing the widespread predictions that Trump couldn't win the Electoral College votes he needed.
Robby Mook, Hillary Clinton's former campaign manager, said false or misleading news was "huge problem" his operation faced, including some evidence that the election meddling came from overseas.
"Look, Jake, I think there's a lot of things we need to examine coming out of this election ... I still think we have to investigate what happened with Russia here. We cannot have foreign, and I would say foreign aggressors here, intervening in our elections."
He continued: "The Russian were propagating fake news through Facebook and other outlets, but look, we also had, and this is with all due respect to Kellyanne and her colleagues, look Steve Bannon ran Breitbart News, which was notorious for peddling stories like this."
Trump has picked Bannon to be a senior adviser in his administration. Bannon is a former executive at Breitbart News, which he's referred to as "the platform for the alt-right," a far-right political movement rife with white nationalist, anti-Semitic and racist ideologies.
Conway was also asked by Tapper whether President-elect Trump's tweet on voter fraud Sunday was presidential behavior.
On Sunday, Trump alleged, without evidence, that "millions of people" voted illegally for Clinton and otherwise he would have won the popular vote in the 2016 election. This was an unprecedented allegation by a president-elect.
"In addition to winning the Electoral College in a landslide, I won the popular vote if you deduct the millions of people who voted illegally," Trump tweeted.
Conway said that because he tweeted it, it was presidential behavior.
"Well he's President-elect so that's presidential behavior yes," she said about the tweet. "The fact is that this man is now President of the United States and he's tackling very big issues ... he is committed to making good on the promises on, frankly, the plans, and he's going to be focused on that. Not everybody trying to nitpick what he does."